The Human Immunodeficiency Virus
A virus is a very small
organism which can only be seen through
a microscope. Unlike other germs, a virus can only reproduce
itself by entering a living cell and taking over some of that
cell's material.
White blood cells called
macrophages (1) and lymphocytes play an important role in HIV
infection. When HIV enters the body, it binds itself to the lymphocytes,
a type of white cells also called "helper cells" because
they "instruct" other cells to fight off "foreign" intruders
such as germs. HIV can enter T4 cells because they have what
is called a CD4 receptor which matches the virus' key. Once HIV
has entered these cells, its genetic material, RNA (ribonucleic
acid), must be changed to match the cells' DNA (deoxyribonucleic
acid). This is achieved with the help of enzymes. The invaded
cells then begin to reproduce the virus, making hundreds of copies
of HIV, which when ready burst out of the cells into the blood
and lymph of their carrier host. T4 cells die about 24 to 36
hours after being infected with HIV. Although the body is able
to replace them, their numbers decrease over time. As these cells
are key agents in the immune response to various infections,
their depletion eventually causes a serious deficit in normal
antibodies, thereby opening the host body to all kinds of opportunistic
infections.
1. This discussion
on the HIV development process is based on material from Patterson
and Robichaud, Managing Your Health, 1996, p.16-17 and 25.
The Stages of HIV Infection
· Window ·
Asymptomatic
Period · Symptomatic
Period · AIDS
The "Window" Period:
This period refers to the
time between the first exposure to HIV and "seroconversion,"
that is the production of antibodies by the immune system in
response to HIV infection. It is only at this point that a blood
test will be positive and this may take anywhere from six weeks
to six months after the initial infection with HIV. Since there
are no obvious symptoms of infection, a person does not know
he or she is infected but can nonetheless infect other people.
The "Asymptomatic" Period:
During this period, which
may last several years, HIV works silently in the carrier host
and slowly but surely destroys the T4 cells. There usually are
no symptoms or there may be swelling of the lymph nodes (neck
and armpits, for example).
The "Symptomatic" Period:
As the immune system is
weakened by the virus, various symptoms develop. Those can include
fever, diarrhea, drenching night sweats, persistent tiredness,
weight loss, and several infections.
Acquired Immune Deficiency Syndrome:
AIDS is the last stage
in HIV infection. At this stage, a person has usually been living
with HIV for many years and the immune system is seriously damaged.
The onset of AIDS is marked by the emergence of severe "opportunistic"
infections which would not develop in an individual with a healthy
immune system. These infections are not directly caused by HIV
but are the consequences of HIV's weakening of the immune system.
Full-blown AIDS is therefore diagnosed by the presence of one
or more specific diseases which are caused by organisms common
in the environment. Such diseases include:
Pneumocystis carinii, which
causes a severe form of pneumonia and is found in about 50 per
cent of AIDS patients (Canada's Blueprint, 1990:9). Women patients,
however, tend to "develop bacterial pneumonia before PCP"
(AFNATF 1994:11). Persons with AIDS also often develop Kaposi's
Sarcoma, a kind of skin cancer, although this is very rare in
women patients (Ibid:10).
Toxoplasmosis, a parasite that infects the brain;
cryptosporidium, a protozoan infection that causes diarrhea,
Herpes simplex I and II viruses, which cause sores on the lips
or genitals that do not heal in the usual seven to fourteen days;
Candida Albicans, which causes vaginitis in otherwise healthy
women, is sometimes found in the throat and lungs of people with
AIDS.
All the above conditions
and several others contribute to an AIDS diagnosis because they
are rarely found in people with healthy immune systems (Idem).
In most cases, one of these infections will eventually cause
the death of the person living with AIDS. There is however, some
variation in the severity of symptoms from one individual to
another and drugs are now available that can reduce HIV's damage
to the immune system and prolong life.
The Transmission of HIV
HIV can be transmitted
from an infected person to someone else when there is an exchange
of blood, semen or vaginal secretions. In addition, a baby born
to an HIV-positive mother has a 14 to 25 per cent chance of being
infected (The College of Family Physicians of Canada, 1995:23).
Requirements for Transmission
(AFNATF:13).
The virus has to be present in
a person's body in sufficient concentration in order to be transmitted.
The virus must get into the other
person's bloodstream to cause infection.
"The behaviors that
can result in HIV transmission are certain sexual activities,
sharing injection drug needles or receiving infected blood or
certain blood products (prior to the screening of blood and blood
products implemented in 1985)" (Idem).
Sexual Transmission
Unprotected sexual intercourse with
same sex or with other sex infected partner, whether anal or
vaginal.
Oral
sex (fellatio - cunnilingus), with an infected person.
Donor
insemination with infected
semen although most semen is now screened for HIV.
Non-sexual Transmission
Sharing injection drug needles with
an infected person. The blood of an infected person can in this
way pass directly into the other person's bloodstream. This is
probably the most efficient way to transmit HIV. One should also
be wary of tattooing needles which may present a risk of infection
if they are not sterile.
Receiving blood transfusions or
blood products coming from infected donors. This risk is currently
minimized as the Red Cross has been screening all blood donations
since November 1995. The currently detected AIDS cases related
to this mode of transmission were more likely transmitted by
blood received before this date.
Prenatal transmission from an infected
mother to her child either prior to birth
at birth, or through breastfeeding, although breastmilk does
not contain high concentrations of HIV.
Needlestick exposures to HIV in the occupational setting can,
in some cases, result in HIV infection. However, this risk is
well known at 0.3 per cent or 3 per 1,000.
It must be pointed out
that HIV cannot be transmitted through saliva, tears, insect bites,
casual contact with infected persons or sharing eating utensils,
pools or hot tubs with them. Kissing a person with HIV/AIDS is
not a risky activity. "Wet kissing" however, could be problematic should one have a cut or sore in the
mouth allowing for the exchange of blood from the infected person.
But there is no evidence whatsoever to show that one can contract
HIV through saliva. The concentration of HIV in saliva is so
minute that one would "have to inject over a quart of it
into one's veins in order to become infected" (Ibid:18).
Tests for HIV Infection
There are two
kinds of tests used to look for antibodies to HIV. The ELISA test, which stands
for "enzyme-linked immunosorbent assay," is done first
(Patterson and Robichaud:23). If the ELISA is positive, a second
test, the Western Blot, is performed to confirm the results.
If both tests are positive, it means that antibodies to HIV are
being produced, indicating the presence of HIV in the body. Viral
load tests can also be performed. These show the actual amount
of HIV present in the blood. They can show whether infection
has occurred even if the immune system has not produced any antibodies
(Idem).
The T4 percentage test
is used to determine the percentage of T4 cells compared to the
total number of lymphocytes in the blood. This, as well as absolute
T4 cell counts, gives an indication of the state of the immune
system. If the number of T4 cells is low, it may be necessary
to start taking action in order to delay further deterioration
of the immune system.
It is worth remembering
that a person may test negative during the "window period." A
second test should be performed at a later date to allow for the production of
antibodies to HIV.
Psycho-social Aspects of Testing for HIV
The patient must be made
aware of the testing procedures and the potential benefits of
testing, but also of the risks and consequences of being found
seropositive (testing positive for HIV). He or she must give
informed consent before being tested. The confidentiality issue
must be discussed regarding the test results and the three possible
options (AFNATF:84).
Nominal testing: The
name of the patient and Medicare number are put on the test requisition.
In this case, positive results are submitted to the Department
of Health. This can lead to identification of the infected persons.
Non-nominal testing: A code disguises the patient's
name on the testing requisition and is known only to physician
and patient. This offers a better protection of confidentiality.
Anonymous testing: The
patient's identity remains undisclosed and the sample is only
identified by a code name and a number given by the clinic's
staff. Some patients prefer this third option to avoid possible
breaches of confidentiality but this type of testing is only
available at certain special clinics.
In the case of a positive
test, the patient has an ethical obligation to inform any sexual
or drug-using partner(s) that they have been exposed to HIV.
If the patient refuses to do so, the physician is obligated to
inform such partners, but only after informing the patient that
this will be done.
Meaning of a Positive Test
Testing positive means
that HIV has entered the body and therefore the whole process
involving the deterioration of the immune system has begun. However,
to prevent or at least delay the onset of AIDS or HIV-related
symptoms, one should (Ibid:85):
